Turbine rotor apparatus and system

ABSTRACT

A segmented turbine rotor is disclosed. The segmented turbine rotor has a plurality of rows of a plurality of turbine blades. At least one rotor segment of a plurality of rotor segments of the segmented turbine rotor includes a ring disposed circumferentially about and having an axis substantially parallel to a central axis of the rotor, the ring defining a cavity disposed at a center thereof and having an outer surface supporting at least one row of the plurality of rows of turbine blades.

BACKGROUND OF THE INVENTION

The present disclosure relates generally to turbines, and particularlyto turbine rotors. Current turbine rotors, such as used within steamturbines for example, may be produced from a large monoblock forging asa single large rotor. Alternatively turbine rotors, such as used withingas turbines for example, may include an assembly consisting of severalwheels, with each wheel including one row of turbine blades thatrepresent a stage of the turbine. The wheels can be welded or boltedtogether. These aforementioned turbine rotor designs result in turbinerotors that have high weight and thermal mass. The weight and thermalmass of current rotor designs result in compromised clearance controland extended turbine starting procedures to accommodate changes in rotortemperature and speed. Accordingly, there is a need in the art for aturbine rotor arrangement that overcomes these drawbacks.

BRIEF DESCRIPTION OF THE INVENTION

One embodiment of the invention includes A segmented turbine rotor. Thesegmented turbine rotor has a plurality of rows of a plurality ofturbine blades. At least one rotor segment of a plurality of rotorsegments of the segmented turbine rotor includes a ring disposedcircumferentially about and having an axis substantially parallel to acentral axis of the rotor, the ring defining a cavity disposed at acenter thereof and having an outer surface supporting at least one rowof the plurality of rows of turbine blades.

Another embodiment of the invention includes a turbine including anouter frame, a segmented turbine rotor disposed within the outer frame,the segmented turbine rotor including a plurality of rotor segments anda plurality of rows of a plurality of turbine blades in operablecommunication with the segmented turbine rotor. At least one rotorsegment of the plurality of rotor segments includes a ring disposedcircumferentially about and having an axis substantially parallel to acentral axis of the rotor, thereby defining a cavity disposed at acenter of the ring, the ring having an outer surface supporting at leastone row of the plurality of rows of turbine blades.

These and other advantages and features will be more readily understoodfrom the following detailed description of preferred embodiments of theinvention that is provided in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the exemplary drawings wherein like elements are numberedalike in the accompanying Figures:

FIG. 1 depicts a schematic drawing of a turbine in accordance with anembodiment of the invention;

FIGS. 2, 3, and 4 depict cross sections of a turbine rotor arrangementin accordance with embodiments of the invention; and

FIG. 5 depicts a cross section of a turbine rotor segment and turbineblade in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

An embodiment of the invention provides a segmented rotor for a turbineincluding welded segments that can include more than one row of turbineblades. The segmented rotor can include one or more rings in conjunctionwith one or more disks and includes a substantially hollow interior toreduce weight and thermal mass of the segmented rotor as compared tocurrent rotor designs.

Referring now to FIG. 1, a schematic drawing of an embodiment of aturbine 20 that uses a plurality of turbine blades in operablecommunication with a rotor 24 to convert thermal and kinetic energy tomechanical energy via rotation of the rotor 24 relative to an outerframe 26 is depicted. The turbine 20 may be a gas turbine, whichconverts thermal and kinetic energy resulting from expansion ofcombustion gasses 12, for providing mechanical energy to propel avehicle, such as an airplane, a ship, or a train for example, forgenerating electricity, or providing mechanical energy for otherapplications, such as pumping, for example. Alternatively, the turbine20 may be a steam turbine, which converts thermal and kinetic energyresulting from expansion of high temperature steam 12 to mechanicalenergy for any variety of uses, such as those described above, forexample.

Referring now to FIG. 2, a cross section of an embodiment of a segmentedrotor 28 is depicted. The segmented rotor 28 includes more than onerotor segment 30, such as rotor segments 32, 34, 36, 38, 40, 42, 44.Turbine blades 48 are arranged upon the segmented rotor 28 in aplurality of rows 52, also known as stages. While only four turbineblades are indicated specifically, it will be appreciated that referencenumeral 48 shall refer to all such turbine blades in general. It will beappreciated that while each row 52 of turbine blades 48 is representedby the turbine blade 48 depicted in FIG. 2, it includes a plurality ofturbine blades 48 that extend circumferentially around a center, orcentral axis 56 of the segmented rotor 28 in line with the turbineblades 48 depicted. At least one of the rotor segments 30, such as thedepicted rotor segments 36, 40, 44, include more than one row 52 ofturbine blades 48.

In an embodiment depicted in FIG. 2, (for purposes of illustration andnot limitation), the segmented rotor 28 includes seven rotor segments32, 34, 36, 38, 40, 42, 44 upon which twelve rows 52 of turbine blades48 are disposed.

With reference in particular to rotor segments 34, 42, also hereinreferred to as “disks” the rotor segments 34, 42 provide a structurehaving a web 144, 148 and a flange 152, 156, defining a general “T”shape in section, as depicted in FIG. 2. In an embodiment, the rotorsegments 34, 42 are one piece “disk” rotor segments having the flange152, 156 integral to the web 144, 148. The web 144, 148 has a first end145, 149 and a second end 147, 151. The first end 145, 149 of the web144, 148 extends radially inwardly toward, and is disposed proximate acenter 56 of the rotor 24. The second end 147, 151 is located near theflange 152, 156, which is oriented about perpendicular to the web 144,148 and disposed circumferentially about the center 56. In oneembodiment, the disk rotor segments, such as disk rotor segment 34 forexample, includes a bore 58, or hole to enable access to the interior ofthe segmented rotor 28 for inspection and any needed dressing to welds,as will be discussed further below.

A first segment, such as the segment 32 for example, is disposedadjacent to a second segment, such as the segment 34 for example, suchthe flange 154 of the first segment 32 contacts the flange 152 of thesecond segment 34. Stated alternatively, the flange 152, 156 is orientedparallel to the center 56, and forms a concentric shell surrounding thecenter 56.

With reference in particular to rotor segments 36, 38, 40, also hereinreferred to as “rings”, the rotor segments 36, 38, 40 provide astructure that is toroidal, having a generally rectangular shape 37 incross section, as depicted in FIG. 2. The toroidal or ring structure ofthe rotor segments 36, 38, 40 defines a cavity or center area of openspace 45, 46, 47, such that the ring rotor segments 36, 38, 40 arehollow. The generally rectangular shape in cross section of the ringrotor sections 36, 38, 40 is disposed circumferentially about the center56. In one embodiment, the rotor segments 36, 38, 40 are one piece“ring” rotor segments 36, 38, 40 that are absent any web extendingradially inwardly, and thereby form a concentric shell that surroundsand has an axis 57 that is substantially parallel to the central axis 56of the rotor 24, similar to the flange 152, 156 of the rotor segments34, 42. In another embodiment the axis 57 of each of the ring rotorsegments 36, 38, 40 is coincident with the central axis 56 of the rotor28. The ring rotor segments, such as ring rotor segments 36, 38, 40include an outer surface 39 that supports one or more rows 52 of turbineblades 48.

FIG. 3 depicts an embodiment of the segmented rotor 28 having analternate arrangement of disk and ring rotor segments. For example, adisk rotor segment 200 is disposed near a center 204 of the rotor 28,adjacent two ring rotor segments 208, 212. In an embodiment, a flange,such as the flange 216 provides a surface 220 opposite the web 224 thatcan support more than one row 52 of the turbine blades 48.

While embodiments of the invention has been described having seven rotorsegments 30 with a total of twelve rows 52 of turbine blades 48, it willbe appreciated that the scope of the invention is not so limited, andthat the invention will also apply to segmented rotors 28 that havedifferent numbers of rotor segments 30 upon which different numbers ofrows 52 of turbine blades 48 are disposed, as may be required byspecific turbine 20 application needs. In an embodiment, the number ofsegments 30, rows 52 of turbine blades 48 per segment 30, can beoptimized based upon stress, manufacturability, cost, and ease ofquality inspection. Further, while embodiments have been described withrespect to particular arrangements of disk rotor segments relative toring rotor segments, it will be appreciated that the scope of theinvention is not so limited, and that invention will also apply tosegmented rotors 28 that utilize different arrangements of disk and ringrotor segments, such as to incorporate an arrangement including havingeach disk rotor segment adjacent a ring rotor segment, for example.

Referring back now to FIG. 2, use of the structure of the rotor segments32, 34, such as two disk rotor segments disposed adjacent one another,described above including the flange 152, 154 and the web 144, 146provide areas of open space 72, 76, or cavities, defined by and disposedbetween the web 144, 146 and the flange 152, 154 of the adjacent rotorsegments 32, 34. The areas of open space 72, 76, provided by disk rotorsegments 32, 34, 42, 44, in addition to the areas of open space 45, 46,47 provided by the ring rotor segments 36, 38, 40 contribute to areduction in weight and thermal mass of the segmented rotor 28 ascompared to current rotor designs.

FIG. 4 depicts an embodiment of the segmented rotor 28 having anarrangement of ring rotor segments 300, 304, 308, 312, absent any diskrotor segments other than rotor segments 316, 318 disposed proximateends 320, 322 of the rotor 28.

With reference back to FIG. 2, in an exemplary embodiment, the rotorsegments 32, 34 are disposed in contact adjacent to one another and arewelded together at a weld joint 60. Similarly, rotor segments 34, 36 arewelded together at a weld joint 64 disposed between the flange 152 ofsegment 34, and the ring of segment 36. In similar fashion rotorsegments 36, 38, rotor segments 38, 40, rotor segments 40, 42, and rotorsegments 42, 44 are welded together at weld joints 68. An embodiment ofthe segmented rotor 28 will use weld joints 60, 64, 68 that have beenproduced by a narrow gap Tungsten Inert Gas (TIG) welding process tominimize an amount of weld material required to join the rotor segments30. It is further contemplated that alternate weld processes, such aselectron beam welding, laser welding, and other welding processes may beutilized to join segments 30. Localized pre-welding heat treatment ofregions 84, 88, 92 of the rotor segments 30 nearest the weld joints 60,64, 68 is contemplated for preparing the rotor segments 30 for welding.Further, localized post-welding heat treatment of the regions 84, 88, 92is contemplated for optimizing the weld properties, such asmicrostructure, residual stress, and distortion, for example. In oneembodiment, two adjacent rotor segments 30 include different, ordissimilar alloy parent materials. Such localized heat treatment iscontemplated to be performed in such a way as to produce a controlledthermal gradient to accommodate welding together the rotor segments 30that include dissimilar alloy parent metals. The localized heattreatment is contemplated to expose each of the rotor segments 30 havingdifferent alloy parent materials to different temperatures to optimizethe properties of each of the dissimilar alloy parent metals across theweld joint 60, 64, 68.

As compared to current gas turbine 20 rotor designs that utilize severalwheels bolted together, with each wheel having one row of blades, thesegmented rotor 28 reduces the weight, thermal mass, and complexityassociated with the multiple wheels and bolts. Reducing the complexityaccordingly reduces a manufacturing cost of the segmented rotor 28.Reducing the weight and thermal mass of the rotor 24 effects the rate ofexpansion and contraction of the rotor 24. Accordingly, use of thesegmented rotor 28, having reduced thermal mass is contemplated toenhance control of the clearances by better matching the rate ofexpansion of the rotor 24 to the expansion of the adjacent turbine 20stationary components. Furthermore, reduction of the weight and thermalmass is contemplated to simplify a starting procedure, as the segmentedrotor 28 will reach steady-state speeds and temperatures within ashorter time interval. In one embodiment, it is contemplated that aweight of the segmented rotor 28 is 40 percent less than a comparablerotor using current design and construction arrangements.

While current steam turbines 20 may use rotors 24 made from materialsthat allow machining of one large rotor 24, contemplated use of advancedmaterials that are better suited to specific operating conditions withinturbines 20 will preclude the machining of one large rotor 24, as suchmaterials are often not available in sizes to that correspond to onelarge rotor 24. Accordingly, use of the rotor segments 30 within a steamturbine is contemplated to facilitate use of a lighter weight rotor 24that incorporates advanced materials. Examples of advanced materialsinclude super alloys such as alloys 718, 706, Rene 95, 625, Nimonic 263and other commercial superalloys for example, Martensitic stainlesssteels, such as M152 (formerly known as Jethete M152), AISI 403, 450 forexample, low alloy steels such as NiCrMoV, CrMoV (ASTM A470) forexample, and Titanium alloys such as Ti-6-4, Ti6Q2, for example. Theforegoing examples are for purposes of illustration, and not limitation.

In an exemplary embodiment, it is contemplated that different rotorsegments 30 are made from different materials, with each rotor segment30 being made from a material that is suited for the particularoperating conditions within the turbine 20 to which it is exposed. Forexample, different rotor segments 30 that are exposed to differingtemperatures, payload, or centrifugal loading that results from blade 48weight, are contemplated to be made from different materials selectedfor their performance relative to the temperature, payload, orcentrifugal loading. Segmented rotors 28 assembled from such rotorsegments 30 made from different materials are further contemplated toutilize a differential post-welding heat treatment, with thedifferential heat treatment optimized to meet the requirements of thedifferent materials.

Referring now to FIG. 5 another embodiment of a rotor segment 96 isdepicted. Dovetail grooves 100 machined into the rotor segment 96provide for a tangential entry assembly of turbine blades, such as aturbine blade 104 that includes a root 108 having a geometry thatmatches the geometry of the dovetail groove 100. The dovetail groove 100is cut into an outer surface 112 of the flange 114.

As disclosed, some embodiments of the invention may include some of thefollowing advantages: a turbine rotor having reduced weight; a turbinerotor having reduced thermal mass; a turbine rotor having a reducedassembly complexity; a turbine having a simplified starting procedure; aturbine rotor having an improved clearance control; a turbine rotorhaving different materials suited for location-dependent operatingconditions within a turbine; and a turbine rotor having a reducedmanufacturing cost.

While the invention has been described with reference to exemplaryembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment disclosed as the best oronly mode contemplated for carrying out this invention, but that theinvention will include all embodiments falling within the scope of theappended claims. Also, in the drawings and the description, there havebeen disclosed exemplary embodiments of the invention and, althoughspecific terms may have been employed, they are unless otherwise statedused in a generic and descriptive sense only and not for purposes oflimitation, the scope of the invention therefore not being so limited.Moreover, the use of the terms first, second, etc. do not denote anyorder or importance, but rather the terms first, second, etc. are usedto distinguish one element from another. Furthermore, the use of theterms a, an, etc. do not denote a limitation of quantity, but ratherdenote the presence of at least one of the referenced item.

1. A segmented turbine rotor having a plurality of rows of a pluralityof turbine blades, at least one rotor segment of a plurality of rotorsegments of the segmented turbine rotor comprising: a ring disposedcircumferentially about and having an axis substantially parallel to acentral axis of the rotor, the ring defining a cavity disposed at acenter thereof and having an outer surface supporting at least one rowof the plurality of rows of turbine blades.
 2. The segmented turbinerotor of claim 1, wherein: the outer surface of the ring supports morethan one row of the plurality of rows of turbine blades.
 3. Thesegmented turbine rotor of claim 1, wherein at least one rotor segmentof the plurality of rotor segments comprises: a web portion having afirst end and a second end, the first end disposed proximate the centralaxis of the rotor; and a flange portion integral with the second end ofthe web portion, the flange portion disposed parallel to the centralaxis, thereby defining a cavity disposed between the web portion and theflange portion, the flange portion having an outer surface supportingmore than one row of the plurality of rows of the plurality of turbineblades.
 4. The segmented turbine rotor of claim 1, wherein: a firstsegment of the plurality of rotor segments is disposed adjacent to andin contact with a second segment of the plurality of rotor segments. 5.The segmented turbine rotor of claim 4, further comprising: a weld jointdisposed between the first segment and the second segment.
 6. Thesegmented turbine rotor of claim 5, wherein the first segment and thesecond segment comprise different materials.
 7. The segmented turbinerotor of claim 1, wherein at least one of the plurality of rotorsegments further comprises: more than one row of a plurality of dovetailgrooves in the outer surface, a turbine blade of the plurality ofturbine blades being retained by each dovetail groove of the pluralityof dovetail grooves.
 8. The segmented turbine rotor of claim 1, whereinat least one rotor segment of the plurality of rotor segments is madefrom at least one of: a super alloy; a martensitic stainless steel; alow alloy steel, and a titanium alloy.
 9. A turbine comprising: an outerframe; a segmented turbine rotor disposed within the outer frame, thesegmented turbine rotor comprising a plurality of rotor segments; aplurality of rows of a plurality of turbine blades in operablecommunication with the segmented turbine rotor; and at least one rotorsegment of the plurality of rotor segments comprising: a ring disposedcircumferentially about and having an axis substantially parallel to acentral axis of the rotor, thereby defining a cavity disposed at acenter of the ring, the ring having an outer surface supporting at leastone row of the plurality of rows of turbine blades.
 10. The turbine ofclaim 9, wherein: the outer surface of the ring supports more than onerow of the plurality of rows of turbine blades.
 11. The turbine of claim9, wherein: a first segment of the plurality of rotor segments isdisposed adjacent to and in contact with a second segment of theplurality of rotor segments.
 12. The turbine of claim 11, wherein thesegmented turbine rotor further comprises: a weld joint disposed betweenthe first segment and the second segment.
 13. The turbine of claim 12,wherein the first segment and the second segment comprise differentmaterials.
 14. The turbine of claim 9, wherein at least one rotorsegment of the plurality of rotor segments comprises: a web portionhaving a first end and a second end, the first end disposed proximatethe central axis of the rotor; and a flange portion integral with thesecond end of the web portion, the flange portion disposed parallel tothe central axis, thereby defining a cavity disposed between the webportion and the flange portion, the flange portion having an outersurface supporting more than one row of the plurality of rows of theplurality of turbine blades.
 15. The turbine of claim 9, wherein atleast one of the plurality of rotor segments further comprises: morethan one row of a plurality of dovetail grooves in the outer surface, aturbine blade of the plurality of turbine blades being retained by eachdovetail groove of the plurality of dovetail grooves.
 16. The turbine ofclaim 9, wherein at least one rotor segment of the plurality of rotorsegments is made from at least one of: a super alloy; a martensiticstainless steel; a low alloy steel, and a titanium alloy.
 17. Theturbine of claim 9, wherein: the turbine is one of a gas turbine and asteam turbine.